Measuring device

ABSTRACT

Herein disclosed is a measuring device such as a micrometer, slide calipers, a depth gauge or a height gauge, in which a slider is so provided that it can move back and forth in the same direction of such a relatively movable portion as can move relative to a frame and that it can be fixed on said frame at any position in the forward and backward moving directions thereof, and in which there is interposed between said slider and said relatively movable portion such spring bias means as can apply its spring force to said relatively movable portion in the forward and backward moving directions of the same, whereby the measuring pressure to be applied to a test piece by said relatively movable portion can be automatically predetermined at a substantially constant level independently of the position of said relatively movable portion relative to said frame.

BACKGROUND OF THE INVENTION

The present invention relates to a measuring device such as amicrometer, slide calipers, a depth gauge or a height gauge andcontemplates to automatically establish a constant measuring pressureindependently of the intention of a measurer.

A measuring device such as a micrometer, slide calipers, a depth gaugeor a height gauge is used to measure the length of a test piece (anobject to be measured) by having its movable portion contacting with thetest piece. The measurement of the length of a test piece by themeasuring device of that type is performed by manually moving themovable portion until its portion contacts with the test piece and byclamping the test piece together with a stationary portion.

As a result, the measuring device has an advantage that the operationcan be performed easily and promptly. However, since the test piece hasto be held by the force of the fingers of the measurer, the indicatedvalues have a tendency to become different in accordance with thechangeable measurers and with the shapes of the test pieces so that themeasurements cannot be always performed accurately.

In view of this tendency, there has been conceived a device, in which aspring is interposed between the movable portion and a lift knob wherethe finger of the measurer is applied to move the movable portion sothat the measuring pressure for holding the test piece may be madeconstant by the elastic force of the spring. The device of this typealso has a tendency that the spring is warped, when the lift knob ispushed by a stronger force than a usual one, thereby to invite similarresults to the aforementioned ones.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide ameasuring device of the type, in which a slider is so provided that itcan move back and forth in the same direction of such a relativelymovable portion as can move relative to a frame and that it can be fixedon said frame at any position in the forward and backward movingdirections thereof, and in which there is interposed between said sliderand said relatively movable portion such spring bias means as can applyits spring force to said relatively movable portion in the forward andbackward moving directions of the same, whereby the measuring pressureto be applied to a test piece (an object to be measured) by saidrelatively movable portion can be automatically predetermined at asubstantially constant level independently of the position of saidrelatively movable portion relative to said frame.

Another object of the invention is to provide a measuring device of thetype, in which a supporting post is fixed to the frame in parallel withthe relatively movable portion and at a spacing from the same and inwhich a slider is slidably held on said supporting post, whereby saidslider is supported on said frame slidably in the same direction as theforward and backward moving directions of said relatively movableportion thereby to facilitate the support of said relatively movableportion on said frame.

Still another object of the present invention is to provide a measuringdevice of the type, in which said supporting post is constructed of twomembers, whereby said slider can be easily and reliably prevented fromrotating in the circumferential direction of said supporting posts.

A further object of the present invention is to provide a measuringdevice of the type, in which the fixing means for fixing said sliderupon the frame is constructed to include: a rack provided at the side ofsaid frame in the same direction as the forward and backward movingdirections of said slider; a pawl held on said slider such that it canmove back and forth relative to said rack; and a spring or the likeinterposed between said pawl and said slider for biasing said pawltoward and into engagement with said rack, whereby said slider can beeasily and reliably fixed on said frame at any position in the movingdirection thereof.

A further object of the present invention is to provide a measuringdevice of the type, in which either said relatively movable portion orsaid slider is equipped with a pair of movement regulating portionsspaced from each other in the forward and backward moving directionsthereof, in which the other of said relatively movable portion and saidslider is equipped with a retaining portion interposed between saidpaired movement regulating portions, in which the spacing between saidpaired movement regulating portions is so predetermined that saidretaining portion can move slightly between said paired movementregulating portions in the forward and backward moving direction of saidrelatively movable portion, and in which a spring acting as said springbias means is interposed between at least one of said movementregulating portions and said retaining portion, whereby said relativelymovable portion and said slider can be connected without any play.

A further object of the present invention is to provide a measuringdevice of the type, in which the rack acting as the fixing means isprovided on said supporting post so that it can be easily worked.

A further object of the present invention is to provide a measuringdevice of the type, in which the spring acting as said spring bias meansis loosely fitted on said supporting post thereby to ensure theretention thereof.

A further object of the present invention is to provide a measuringdevice of the type, in which the rack acting as the fixing means isprovided on one of the two supporting posts whereas the spring acting assaid spring bias means is loosely fitted on the other of said twosupporting posts, whereby the mounting capability and workability of theparts can be improved.

A further object of the present invention is to provide a measuringdevice of the type, in which said lift knob is made integral with thepawl acting as said fixing means, whereby the operations of said sliderand said pawl can be simultaneously performed.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a partially sectional view showing a measuring deviceaccording to one embodiment of the present invention; and

FIG. 2 is a sectional view taken along line II--II of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

One embodiment, in which the present invention is applied to amicrometer, will now be described with reference to the accompanyingdrawing. Indicated at reference numeral 1 is a first frame generallyhaving a shape of letter "U", which is disposed at the side of ameasuring portion and which has its leading end attached with an anvilportion 2 at its inside and its trailing end jointed to a second frame 3acting as a fixing portion. The second frame 3 is supported on thetrailing ends of the first frame 1 by means of two supporting posts 4and 5. These supporting posts 4 and 5 are fixed to the frame 1 inparallel with and at a spacing from each other. Thus, an integralsupporting frame is constituted by these frames 1,3 and the twosupporting posts 4,5.

Indicated at reference numeral 6 is a spindle acting as a relativelymovable portion or first adjustable element, which is supported slidablyback and forth relative to the anvil 2 by means of holes 7 and 8 suchthat it can be moved by the operation of a later-described lift knob 9from the position, where its leading end (or the lefthand end, as shown)abits against the anvil 2, through the position in the drawing to therighthand position. Since the frame 3 is covered with a case 10, thelift knob 9 protrudes to the outside thereof. Incidentally, theaforementioned supporting posts 4 and 5 are arranged in parallel withand at a spacing from the spindle 6.

A block member 11 is integrally attached to the spindle 6 by means of ascrew 12. To this block member 11, there is fixed the front end side ofa glass scale 13 which is disposed not to contact with the frame 3. Thisglass scale 13 is formed on its transparent glass body with graduationsin μ (which are not actually seen unless they are enlarged but which areshown in an enlarged scale for understanding convenience). To the frame3 integrally interconnecting the supporting posts 4 and 5, there arearranged both a not-shown light emitting element and a photoelectricconverting element 15 at positions across the glass scale 13 such thatthe light emitted from the light emitting element may pass through theglass scale 13 until it reaches the photoelectric converting element 15.As a result, the brightness of the light to reach the photoelectricconverting element 15 is changed in accordance with the movement of thespindle 6. The resultant change in the brightness is converted by theelement 15 into electric signals, which are counted by a countingcircuit so that their values are displayed in a liquid crystal displayplate 16 which is mounted on the surface of the case 10. In this case10, there is arranged a print substrate 17 such that the aforementionedelectric processing is performed.

The supporting posts 4 and 5 constitute a portion of the second frame 3and are arranged in parallel with the spindle 6. A slider 18, whichforms a second adjustable element is so held on those supporting posts 4and 5 that it can move in the same direction as the forward and backwardmoving directions of the spindle 6. The slider 18 thus mounted is formedinto a U-shape, as shown, and is formed with movement regulatingportions 18a and 18b which are spaced from each other in the forward andbackward moving directions of the spindle 6. Into the opening betweenthose movement regulating portions 18a and 18b, an arm (or dependingretaining portion) 19 is inserted, which forms a part of the blockmember 11. Between the opening of the slider 18 and the arm 19,moreover, there is interposed under compression a spring 21 acting asspring bias means for biasing the spindle 6 into contact with a testpiece (an object to be measured) or workpiece 20. The test piece orworkpiece 20 has a linear dimension to be measured between two opposedsides thereof.

As a result, the force of the spring 21 is applied to the spindle 6through the block member 11 and the arm 19 constituting a part of theformer so that the spindle 6 is biased to move in the leftwarddirection, as shown, relative to the slider 18. Incidentally, thismovement has its limit at the position, where the arm 19 contact withthe inside of the lefthand porton (i.e., movement regulating portion18a) of the opening of the slider 18, as shown.

A pawled arm 22 acting as a portion of the fixing means has its baseportion pivotally connected to the slider 18 by means of a pivot pin 23.The rotating force in the counter-clockwise direction, as viewed in FIG.1, is effected by a spring 24 (forming a part of the fixing means) whichis wound on the pivot pin 23. This spring 24 has its one end retained ata portion of the slider 18 and its other end retained on the pawled arm22 (forming a part of the fixing means).

The pawled arm 22 has its leading end portion formed with a pawl 25,which can engage with a rack 26 (as shown in FIG. 2) formed in the samedirection as the forward and backward moving directions of the spindle6. The pawl and rack form a ratcheting mechanism. The shape of the teethof the rack 26 need not have a triangular section, as shown, but may berectangular. Here, the spacing between the teeth should be made as smallas possible.

The portion of the leading end of the pawled arm 22, which is located atthe back of the pawl 25, is raised to form an upright portion 27, to theleading end of which the lift knob 9 is attached. As a result, thepawled arm 22 can be made to bring its pawl 25 into and out ofengagement with the rack 26 by moving the lift knob 9 up and down inFIG. 1. As shown in FIG. 2, incidentally, the case 10 has its portionextending backward so that a battery 28 acting as a power source isaccommodated in the extension.

The micrometer having the construction thus far described is used in thefollowing manner. First of all, before the measuring condition shown inFIG. 1 is taken, the lift knob 9 is pushed to position the spindle 6 atits right position. When the pawled arm 22 is slightly turned clockwiseon the pivot pin 23 by pushing the lift knob 9 upward in FIG. 1 from theaforementioned condition, the pawl 25 is disengaged from the rack 26.

When, under this condition, the lift knob 9 is pushed leftward in FIG.1, the slider 18 is also moved leftward. Since, at this instant, thespring 21 pushes the arm 19, the spindle 6 is moved leftward through theblock member 11. At this time, the glass scale 13 is also moved so as tooperate the circuit, which is assembled in the print substrate 17,together with the photoelectric converting element 15. As a result,value of the movement is detected and displayed in the liquid crystaldisplay plate 16.

When the spindle 6 is moved leftward in that way until it holds the testpiece 20 together with the anvil 2, as shown in FIG. 2, it receives areaction so that it does not move any more in the leftward direction.Even if it is tried to advance the slider 18 by means of the lift knob 9under that condition, then the spring 21 is warped to prevent furtheradvance so that the force of the spring is exerted as the measuringpressure at a constant level upon the spindle 6. When the finger of themeasurer is released from the lift knob 9, that particular conditionwill continue.

Although the embodiment thus far described is the case, in which thepresent invention is applied to the micrometer, the present inventioncan also be applied to the measuring device other than the micrometer,such as the slide calipers, the depth gauge or the height gauge. In thiscase, it is sufficient to provide another relatively movable portion atthe back portion of the auxiliary scale which is intrinsically therelatively movable portion, to provide retaining means having a pawl anda rack at the relatively movable portion added, and to interpose aspring between the additional movable portion and the auxiliary scale.

As has been described hereinbefore, according to the present invention,since a slider is so provided that it can move back and forth in thesame direction of such a relatively movable portion as can move relativeto a frame and that it can be fixed on said frame at any position in theforward and backward moving directions thereof, and since there isinterposed between said slider and said relatively movable portion suchspring bias means as can apply its spring force to said relativelymovable portion in the forward and backward moving directions of thesame, the measuring pressure to be applied to a test piece (an object tobe measured) by said relatively movable portion can be automaticallypredetermined at a substantially constant level independently of theposition of said relatively movable portion relative to said frame.Moreover, in case this construction is used in the micrometer as in theaforementioned embodiment, after the test piece is held between theanvil and the spindle, the force for pushing the lift knob is isolatedfrom the spindle thereby to invite an advantage that there is nomeasuring error established, as is different from the prior art. Stillmoreover, since the construction itself is simple, the present inventioncan be applied not only to the micrometer, as exemplified, but also tothe measuring device such as the slide calipers or the height gaugewithout any difficulty. In either application, there can be attainedadvantages that the size of the device can be reduced and that theusability at an equal level to the prior art can be ensured.

According to the present invention, furthermore, since a supporting postis fixed to the frame in parallel with the relatively movable portionand at a spacing from the same, and since a slider is slidably held onsaid supporting post, said slider is supported on said frame slidably inthe same direction as the forward and backward moving directions of saidrelatively movable portion thereby to facilitate the support of saidrelatively movable portion on said frame.

Since said supporting post is constructed of two members, said slidercan be easily and reliably prevented from rotating in thecircumferential direction of said supporting posts.

Since the fixing means for fixing said slider upon the frame isconstructed to include: a rack provided at the side of said frame in thesame direction as the forward and backward moving directions of saidslider; a pawl held on said slider such that it can move back and forthrelative to said rack; and a spring on the like interposed between saidpawl and said slider for biasing said pawl toward and into engagementwith said rack, said slider can be easily and reliably fixed on saidframe at any position in the moving direction thereof.

Since either said relatively movable portion or said slider is equippedwith a pair of movement regulating portions spaced from each other inthe forward and backward moving directions thereof, since the other ofsaid relatively movable portion and said slider is equipped with aretaining portion interposed between said paired movement regulatingportions, since the spacing between said paired movement regulatingportions is so predetermined that said retaining portion can moveslightly between said paired movement regulating portions in the forwardand backward moving directions of said relatively movable portion, andsince a spring acting as said spring bias means is interposed between atleast one of said movement regulating portions and said retainingportion, said relatively movable portion and said slider can beconnected without any play.

Since the rack acting as the fixing means is provided on said supportingpost, it can be easily worked.

Since the spring acting as said spring bias means is lossely fitted onsaid supporting post, its retention can be ensured.

Since the rack acting as the fixing means is provided on one of the twosupporting posts whereas the spring acting as said spring bias means isloosely fitted on the other of said two supporting posts, the mountingcapability and workability of the parts can be improved.

Since said lift knob is made integral with the pawl acting as saidfixing means, the operations of said slider and said pawl can besimultaneously performed.

What is claimed is:
 1. A measuring device for measuring a lilneardimension of a workpiece wherein the linear dimension is measuredbetween two opposed sides of the workpiece, the measuring devicecomprising:a frame having an anvil portion and supporting portionwherein the workpiece is positioned with one side against the anvilportion and the other side adjacent to the supporting portion; a firstadjustable element having a surface thereon for engaging the other sideof the workpiece; means for reciprocally mounting the adjustable elementon the supporting portion of the frame with the workpiece engagingsurface positioned opposite the anvil portion of the frame whereby theworkpiece is disposed between the anvil portion and workpiece engagingsurface during utilization of the measuring device; a second adjustableelement reciprocally mounted on the frame for motion paralleling that ofthe first adjustable element, the second adjustable element having apair of opposed surfaces defining a space therebetween; a dependingportion on the first adjustable element positioned between the opposedsurfaces; spring means disposed between the depending portion and one ofthe opposed surfaces for biasing the first adjustable element toward theanvil; ratchet means disposed between the second adjustable element andthe frame for preventing movement of the second adjustable element in adirection away from the anvil portion while permitting movement in adirection toward the anvil portion while the ratchet means is engaged;means for normally holding the ratchet means engaged; handle means forreleasing the ratchet means and for reciprocating the second adjustableelement with respect to the anvil, and means on the frame for indicatingthe distance between the anvil portion and workpiece engaging surface ofthe first adjustable element to thereby display the linear dimension ofthe workpiece when the workpiece is disposed between the anvil portionand workpiece engaging surface; whereby, when the workpiece is disposedbetween the anvil portion of the frame and the workpiece engagingsurface of the first adjustable element, the spring means exerts theforce necessary to keep the workpiece engaging surface in abutment withthe side of the workpiece and thus isolates the holding force from thatprovided by the measurer.
 2. The measuring device of claim 1 wherein thespring means is a coil spring in compression between the dependingportion of the first adjustable element and the opposed surface of thesecond adjustable element which faces toward the anvil portion of theframe.
 3. The measuring device of claim 2 wherein the first and secondelements are mounted on surfaces of the frame which extend perpendicularto the anvil portion whereby the first and second elements reciprocatenormally and in a straight line with respect to the anvil portion. 4.The measuring device of claim 1 wherein the first and second elementsare mounted on surfaces of the frame which extend perpendicular to theanvil portion whereby the first and second elements reciprocate normallyand in a straight line with respect to the anvil portion.
 5. Themeasuring device of claim 2 wherein the ratchet means includes a pawlmounted on the second adjustable element and the means for releasing theratchet means includes a handle attached to the pawl, which handle isalso utilized to position the second adjustable element and thus thefirst adjustable element with respect to the anvil portion of the frame.